Suction cup construction and apparatus



Jan. 18, 1966' J- E. OLSON 3,230,002

SUCTION CUP CONSTRUCTION AND APPARATUS Filed April 22, 1963 JOHN 5 0L50A! INVENTOR. BY

BUG/(HORN, BLORE; KLAROU/ST 8 SPAR/(MAN AT T OR/VE Y5 United StatesPatent C) 3,230,002 SUCTION CUP CONSTRUCTION AND APPARATUS John E.Olson, Portland, reg., assignor to Hyster Company, Portland, 0reg., acorporation of Nevada Filed Apr. 22, 1963, Ser. No. 274,733 6 Claims.(Cl. 294-64) This invention relates to improvements in flexible suctioncups and suction cup systems and apparatus.

It is well known that a flexible suction cup tends to distort under loadand will contract under substantial axial loading. As the cup contractsits effective area is reduced to proportionately reduce its capacity tosupport a load.

It is an object of the present invention to provide a flexible cup soconstructed that it is prevented from contracting inwardly of apredetermined limit, to thereby maintain its holding power.

It is current practice in suction cup load handling apparatus to providea cup having a diameter of such magnitude that there is a 100% safetyfactor in relation to the loads to be handled. Such a cup will not dropa load if there is a sudden increase in loading, as for instance whenthe apparatus, such as a vehicle, rides over a bump or a depression.Otherwise a cup of such excess size would not be required. Because theloads are frequently porous, a constant pumping of air must bemaintained to maintain the desired subatmospheric pressure over theentire area of the cup face in spite of infiltration of air through theload. Thus it is undesirable to have the effective vacuum area anylarger than necessary.

Another object of the invention is to provide a cup designed so thatnormally it has a smaller effective area than heretofore provided, butwhich is capable, under emergency conditions, of having a largereffective area, thus to make it possible to utilize a smaller capacityvacuum pump.

In multiple suction apparatus of the type shown in my prior copendingapplication entitled, Suction Apparatus and Method for Picking UpArticles, Especially Paper Rolls, Serial No. 64,639, filed October 24,1960, which has matured into Patent No. 3,147,872, the arrangement issuch that when the cups are connected to the source of vacuum, thepressure drop across the pressure controlled valves of the cups issuflicient to close them. After engaging a load, leakage across thevalves will enable the valves of the cups which fully engage the load toreopen to create rapidly a subatmospheric pressure at the faces of suchcups. The delay which occurs before the Valves reopen, while seeminglybrief, accumulates during a days operation and thus makes the loadhandling longer by the amount of such cumulative time.

It is another object of the invention to provide a multiple suction cupapparatus so designed that the source of vacuum is not capable ofclosing the valves of the cups when all the cups are exposed, but iscapable of closing such valves when at least one cup is fully covered bythe load, whereby the valves of the cups which engage a load will beopen upon engaging a load and will remain open, while the remainingvalves will close to save work on the pump.

Various other objects of the invention will be apparent from thefollowing description taken in connection with the accompanying drawingswherein:

FIG. 1 is a side view of a lift truck having a suction type load pick upmeans embodying the concepts of the present invention;

FIG. 2 is a front elevational view of a suction cup of my invention;

FIG. 3 is a side elevational view of the cup, with parts broken back toa mid-section line;

FIG. 3A is an enlarged fragmentary sectional view of the valve portion Vof FIG. 3;

FIG. 4 is an enlarged fragmentary vertical sectional view taken alongline 4-4 of FIG. 3;

FIG. 5 is a view similar to FIG. 3 but showing the cup under internalsubatmospheric pressure;

FIG. 6 is a fragmentary radial section through the marginal portion of amodified cup; and

FIG. 7 is a vertical section taken along line 77 of FIG. 6.

Referring to FIG. 1, a lift truck T has a mast 6 along which a loadcarriage 7 is elevated in conventional fashion. The carriage has ahorizontal support member 8 for supporting a plurality of suction cupsC1, C2, and C3. The cups are supplied with vacuum by a hose 9 which isconnected at one end to a source of vacuum S on the truck body and isconnected at its opposite end to a manifold 10. The latter is connectedto the cups C1, C2, and C3 through a valve V for each cup. Thus the cupscan support a load L when the cups are supplied with vacuum.

Referring to FIGS. 2-5 each suction or vacuum cup shown comprises a body11 of elastomer material formed in the shape of a cup, which may beconsidered as being of generally conical form. The housing 13 (FIG. 3)of a valve V is partially embedded in the body 11 in a coaxial relationto said body.

The body 11 decreases in thickness toward the peripheral margin thereof,and because of this and the larger circumference of the margin ascompared to the central body portion, the margin is sufficientlyflexible to enable it to conform to irregularities of the load surfacewhich it engages.

A closed coil spring 17 of overall circular form is totally or almosttotally embedded in the marginal portion of the cup body in concentricrelation to the axis of such body. This coil spring will readily permitthe marginal portion of the body to expand (FIG. 5), and to contractfrom such expanded position back to its undeformed condition (FIG. 3),but will function to prohibit contraction of the marginal portioninwardly of the FIG. 3 position, because of the engagement or abutmentof the adjacent coils with one another. It is pointed out that since thecoils are embedded in the body, lateral displacement of the coils isprevented. Another way of considering the coil spring is that while byitself as a column, its 1./r. is rather poor, when embedded in the body,its l./r. is increased sufliciently to enable it to resist contractionof the body inwardly of the FIG. 3 position.

In operation, as the loading on the cup increases, it will tend tocontract from its FIG. 5 position, and will be allowed to contractsomewhat. However, since contraction decreases the total area undersubatmospheric pressure, it is apparent that the cup would soon drop theload if unlimited contraction were permitted. However, the coil spring17 limits such contractive movement and thus enables the cup towithstand greater loading than heretofore possible.

The cup in FIGS. 2-5 has another novel feature in the form of anoutwardly projecting auxiliary lip 19 which is disposed inwardly of andconcentric with the outer lip 21 of the cup. The inner lip also projectsforwardly of the immediately adjacent front surface portions of the cupfor ready contact with a load. However, the lip 19 is disposedrearwardly of the lip 21 when the cup is free as in FIG. 3. A recess 23is formed back of the lip 19 so that when the cup is passed against aload, the cup will tend to have a pronounced flexing at the location ofthe recess to thus tend to project the auxiliary lip for- 3 Yardlyas-shown in -FIG. 3 for ready contact with the oad.

The area of the cup inwardly of the inner or auxiliary lip 19 issufficient to support a load under normal operating conditions. If thereis a sudden increase in loading, such as might occur when the-lift truckT runs over a bump or a depression, the inner lip 19 may be torn awayfrom the load; However, the outer lip 21 will still be in engagementwith the load and thus the effective area of the cup will be increasedsubstantially. Since the subatmospheric pressure will now be effectiveover a larger area, a greater holding force will be produced to enablethe cup to continue to support the load despite the increased loading.After the emergency is over, the in ner lip will resume full contactwith the load. Because of normal air leakage at the outer'lip (orthrough the load) the area between the inner and outer lips will soondrop to substantially atmospheric because this outer area is not incommunication with the pump.

One advantage of inner lip cup construction is that with porous loads,such as those which are wrapped or enclosed in paper products, the.amount of air drawn from the load will be proportional to the effectivearea of the cup. When effective area is determined by the inner lip, itis apparent that the amount of leakage air is less than when theeffective area is determined by the outer lip. Thus the work done by thevacuum pump in maintaining a desired subatmospheric pressure is lesswith a cup having an inner lip because during the major portion ofoperating time, the effective area of the cup is determined by the innerlip 19.

Each valve V includes the valve body 13 within which is a movablevalvemember 25 (FIG. 3) urged by a light coil spring 27 away from avalveseat 28; The valve member is slidably mounted on a pin 29 formovement toward and away from the seat, and the valve member is formedwith a small leakage passage 30 therethrough. The pin 29 is supported bya spider 31 on the body 13.

Adjustment of the at-rest position of the valve member 25 is attained bymeans of a screw 33, which is threaded into the valve member. The headof the screw abuts against a spider-like retainer 35 which is held inplace by a split ring 37.

Thehead of the screw 33-has a non-circular socket or recess 39 toreceive a mating wrench to enable adjustment of the screw relative tothe valve member and hence adjustment of the clearance between the valvemember and the seat 28.

The screw 33 is of the lock type, having a nylon insert 41 so as toreleasably hold the screw in any position of adjustment. The screw can,for instance, comprise a standard Allen-head cap screw with nylonlocking insert.

In operation, if the rush of air through the valve is sufi'lcient tomove the valve member 25 to its closed position, the valve may stillreopen if subsequently the associated cup fully engages a load. This isso because air drawn through the leakage passage 30 will decrease thedifferential pressure across the valve and allow the spring to move thevalve member to its open position.

FIGS. 6 and 7 show a modified form of the inventionin which thearticulated contraction limiting member is in. the form of a number ofdisks 51. These disks are arranged in.overall circular or ring fashionwith the axes of the disks coaxial with the ring axis and with adjacentdisks in contiguous relationship. The disks are embedded in the body 11aof the cup like the coil spring 17. The disks limit contracting movementof the cup in a manner, similar to that of the coil spring 17; For easeof manufacture discs may each have a hole in the center so they may bestrung on a central cord like beads.

It is pointed out that while a cup may have both an auxiliary lip and acontraction limiting means, it could have only one.

Referring to FIG. 1, the vacuum sourceis selectedto.

have a capacity such that the source cannot draw suflicient air throughthe valves V to close them. However, the capacity of the pump is suchthat if one of the cups is fully covered, such as by engaging a load,sufficient air is drawn through the remaining valves to close them.Thus, only the cups whose valves fully engage the load are open, and thevalve of the cup that did fully engage the load was open at'the timesuchcup engaged the load.

The selection of a vacuum source of a desired capac ity, mentionedabove, is only approximate, and. the de: sired action of the valves isthereafter attainedby selecting valve springs which supply the desiredresistance and by adjusting the screws 33 of the valves to getthedelicate adjustment desired. I

Having described the invention in what is considered.

to be the preferred embodiment thereof, it is desired that it beunderstood that the invention is not to be limited other than by theprovisions of'the following claims.

I claim:

1. A suction cup comprising:

a cup member formed of elastomer material and being generally of conicalform,

a closed coil spring of overall annular form embedded in the marginalportion ofv said cup member to limit contraction of said marginalportion but permit expansion thereof and also flexing thereof in anaxial direction.

2. A suction cup comprising:

an elastomer body member of cup form which expands upon contact with aload and tends to contract when supporting a load,

means for limiting contraction of said body member toward the axis ofsaid bodymember;

said means being a closed coil spring embedded in said;

body member adjacent the periphery thereof.

3. A suction cup comprising:

an elastomer body member having a peripheral lip for sealingly engaginga load,

a second lip formed on said body inwardly of saidi peripheral lip forengaging said load and normally forming a seal therewith,

said peripheral lip forming a seal with a load whenever the seal of.said second lip is broken so that the cup has a large effective areauntil said second-lip again resumes its sealed relation to the load,

said second lip being spaced axially inwardly of said peripheral lip inthe' undeformed condition of said body member,-

said body member abruptly changing in thickness at said second lip sothat said second lip is projected forwardly upon flexing of said bodymember,

an articulated means carried by the peripheral margin of said bodymember outwardly of said second lip,: the nature of said articulatedmeans being such-that it permits outward expansion of said peripheralmargin upon engagement with a load but prevents inward' contractivemovement of said peripheral. margin substantially beyond the undeformedposition of said marginal portion.

4. In combination:

a plurality of suction heads,

a common source of vacuum for said heads,

and normally open valve means for controlling the communication of saidsource with said heads,

said valve means being pressure responsive to indi-' vidually close offcommunication between said heads; and source when subjected to apredetermined differ-- ential pressure,

said source having an insufficient capacity to create said differentialpressure when all the heads are exposed to .the ambient air but being socapable when a predetermined number of said heads are covered, and saidvalve means being operable under: the lat ter circumstances to closeonly in relation to the heads which are exposed,

each suction head having an elastomer body and articulated means ofoverall annular form carried by said body member, said articulated meansbeing expansible beyond its original circumference and being fixedagainst contraction inwardly beyond said original circumference so as toprevent contraction of said elastomer body member inwardly toward theaxis of said body member, for preventing contraction of said elastomerbody,

and an auxiliary lip inwardly of said marginal lip portion for normallyengaging a load and forming a seal therewith.

5. A suction cup comprising:

an elastomer body member of cup form which expands upon contact with aload and tends to contract when supporting a load,

means for limiting contraction of said body member toward the axis ofsaid body member and for permitting expansion of said body member awayfrom said axis,

said means being of overall annular form and embedded in said bodymember adjacent the periphery thereof, and being expansible outwardlybeyond its original diameter but fixed against contraction substantiallyinwardly of said original diameter.

6. A suction cup comprising:

a cup member having an elastomer marginal portion,

and means carried by said marginal portion for preventing contraction ofsaid marginal portion but permitting it to flex and expand,

said means being of overall annular form and comprising a series ofportions of relatively incompressible material as compared to saidelastomer marginal portion,

said portions being separable from one another to increase thecircumference of said annular means, and being contractible to positionsin abutment with one another to define the inner limit of contraction ofsaid annular means.

References Cited by the Examiner UNITED STATES PATENTS 1,402,144 1/1922Burke 29464 X 2,229,375 1/ 1941 Eggleston 29464 X 2,776,857 1/ 1957Heppenstall 29464 3,063,746 11/ 1962 Oakes 294-64 FOREIGN PATENTS396,668 6/ 1924 Germany.

928,157 5/ 1955 Germany. 1,252,014 12/1960 France.

GERALD M. FORLENZA, Primary Examiner.

ERNEST A. FALLER, SAMUEL F. COLEMAN,

Examiners.

1. A SUCTION CUP COMPRISING: A CUP MEMBER FORMED OF ELASTOMER MTERIALAND BEING GENERALLY OF CONICAL FORM, A CLOSED COIL SPRING OF OVERALLANNULAR FORM EMBEDDED IN THE MARGINAL PORTION OF SAID CUP MEMBER TOLIMIT CONTRACTION OF SAID MARGINAL PORTION BUT PERMIT EXPANSION THEREOFAND ALSO FLEXING THEREOF IN AN AXIAL DIRECTION.